Product dispensers consisting of containers closed by a pierceable membrane are well known and are commonly employed, for example, in adhesive containers where the sealing of the container by the membrane at one end of the container protects the contents against the adverse consequences of exposure to the environment during shipment and storage. It has been known to provide such containers with dispensing nozzles extending from the membrane area which carry overcaps having moveable plungers or pins that project through the lumen of the nozzle and which can be activated to pierce the membrane. Upon piercing the membrane and removal of the overcap, the contents of the container can be dispensed through the nozzle to a desired location. Upon recapping the nozzle with the overcap with the pin in its piercing position, the pin will reenter the pierced opening in the membrane to partially or substantially reseal the container.
Such moveable pin membrane piercing containers are shown, for example, in U.S. Pat. Nos. 6,726,060 and 5,799,829. Such known containers are formed as metal tubes having an open end opposite the membrane-closed end. The open end is used for filling the container and it may then be closed by a securely fastened plug. While such containers are particularly applicable for use with cyanoacrylates, they are not preferred for other adhesives, such as anaerobics, particularly where chemical interaction may occur with a metal container. In such instances a plastic container may be preferred.
Since plastic containers are often formed by a blow molding process, it is necessary to mold the container with an opening, however for a number of reasons, including the difficulties associated with properly securing a closure plug, such containers are most frequently blow molded from the end of the container forming the dispense opening.
A common form of such a container may, for example, employ a projecting neck which defines a throat opening which may also be used to fill the container and which may thereafter be closed by a cap or, in some instances, by a combination of a sealing foil and cap. The use of peelable sealing foils adhesively or otherwise secured at the neck end closing the throat opening is also a well known way of protecting the contents, after filling, from environmental degradation. Such foils may be constructed of various materials and may be cut, stripped, peeled or pierced to gain access to the contents of the container.
Where it is desired to provide such a container with a foil that is to be pierced to provide an opening, it is generally preferred to form such foils of materials that are relatively susceptible to piercing, such as paper, thin metal foils or the like. Because most plastics have a relatively high degree of elasticity, they are generally not suitable for closure foils where it is intended that the foil be pierced. Such plastics have a tendency to stretch, dimple and then tear when subjected to a piercing operation and would therefore be contraindicated for a pierceable container closure, even though a plastic material closure may have other advantages depending on the contents of the container.
A further disadvantage arises with the use of foil-like closures at the throat opening. Because such closures must be affixed to the open end of the neck, particularly where a cap is to be placed over the neck, the available surface for attachment is limited to the annulus formed at the neck top, which annulus defines the throat opening. Not only does this limit the security of the attachment of the sealing foil to the container, it adversely interferes with obtaining a good seal at the throat when the initial cap structure carried at the throat is a dispensing nozzle, having a lumen opening through it. Where the dispensing nozzle cap is to be attachable to the container prior to removal or piercing of the foil, the dispensing nozzle cannot be provided with any portion thereof projecting into the throat opening as that would interfere with the closure foil. Upon removal or piercing of the closure foil, then the seal formed between the dispensing nozzle cap and the container is limited to the annulus area which can provide a leakage path to the outside surface of the neck.
While the structure disclosed in U.S. Pat. No. 6,726,060 avoids the leakage path problem at the intersection of the throat opening and the dispensing nozzle cap, it does so by positioning the closure membrane axially spaced from the throat opening and providing a frustoconical extension on the undersurface of the nozzle cap which extension extends into the throat opening as a plug and which provides an edge seal at the i.d. of the open end of the throat. Such a seal cannot be provided in connection with a throat covering foil seal.
It would therefore be an advance in the art to provide a dispensing container and cap assembly having a pierceable membrane sealing a throat opening of the container, where the container is initially formed with an open throat and where the membrane is positioned to allow an edge seal to be created at the i.d. at the open end of the throat. It would be a further advance in the art to provide a plastics material membrane in such an assembly.